Switching mechanism



Nov. 7, 1939. A. E. BAAK SWITCHING MECHANISM Filed May '7, 1957 @j 45 If Patented Nov. 7, 1939 UNITED STATES PATENT OFFICE SWITCHING MECHANISM Application May 7, 1937, Serial No. 141,302

' 26 ciaims.

This invention relates to switching mechanism and more particularly to that type of mechanism adapted to open and/or close an electrical circuit, or circuits in response to variations in the value of a condition, to operate suitable mechanism to control the condition.

One object of this invention is the provision of an improved means for adjusting the differential of such a switching mechanism whereby the condition value at which the switch is, illustratively, closed may be varied and the value at which the switch is, illustratively, opened may also be varied independently of the former value.

An additional object resides in the provision of such a differential adjustment means having a visual indicator for each of the condition values above mentioned whereby the same may be readily determined.

A furthe;` object resides in the construction of a simplified differential mechanism having a relatively small number of operating parts and one which will be reliable in operation and adapt itself to exact calibration.

A further object is the provision of such a mechanism which is sturdy, durable, reliable in operation and relatively inexpensive to construct.

Other objects will in part be obvious and in part pointed out hereinafter. f

The invention accordingly consists in the combinations of elements, arrangements of parts and features of construction, all as will be more fully pointed out hereinafter and disclosed in the accompanying drawing wherein:

Figure 1 is a front elevational view of one form of mechanism embodying the instant inventive concept, i

Figure 2 is a side sectional View taken along the line 2 2 of Figure 1 as viewed from the right,

Figure 3 is a fragmentary view showing certain parts of the mechanism as shown in Figure 1, certain other parts thereof being broken away for the sake of clarity,

' Figure 4 is a side elevational view of the mechanism shown in Figure 1 as viewed from the left, certain portions being cut away, and

Figure 5 is a perspective view showing details of construction.

Similiar reference characters refer to similar parts throughout the several views of the drawing.

Having now particular reference to the drawing, there is generally indicated at I0, a casing to which is secured irr any suitable manner a housing Il, which contains a conventional Sylphon belcertain (Cl. 20o-83) bellows is caused to contract and expand in a known manner in accordance with changes in temperature or pressure in any space the condition value of which it is desired to control, as by means of a capillary tube and volatile iluid lled bulb (not shown) or a conventional pressure tube leading from the said space to housing I l.

An operating rod I2 is secured to the bellows and ca'used to move upwardly or downwardly thereby, as is well known in the art. Operating rod l2 is provided with a pointed tip i3, as best shown in Figure 2, which engages a recess in a boss I4 which comprises a portion of a lever I5, lever l5 being freely mounted on point I3 in such manner that it may pivot or oscillate freely thereon subject to limitations by structure to be hereinafter pointed out.

Lever l5 is provided at its extremities with a pair of points H6 and Il which engage suitable recesses in bosses i8 and I9 respectively. Boss I 8 is carried by a lever 20, and boss I9 by a lever 2i.

Levers 2li and 2l are fulcrumed on a member generally indicated at 25 secured as by screws 26 to the base of casing I0. As better shown in Figure 5, member 25 comprises an upwardly extending portion 2'l provided at its upper extremity with a transversely extending portion 28 to which latter are secured a pair of knife edged elements 29 and 30 positioned for engagement with suitable knife edge receiving grooves in levers 20 and 2I respectively. Knife edge members 29 and 30 may be secured to transversely extending portion 28 as by screws 3| in order that the same may be readily removed for replacement in the event that such replacement is necessary or desirable.

Having particular reference to lever 20, the same is provided with an aperture "through which passes a screw 40 provided with a head 4I carrying projections 42 thereon. Screw 40 threadedly engages a boss 43 to which is secured one end of a coil spring 44. The other end of coil spring 44 is secured to a second boss 45 provided with an extending projection 46. A screw 41 provided with an enlarged head 48 extends through the top wall of casing I0 and threadedly engages boss 45. Projection 46 extends outwardly through an aperture 50 in the side wall of casing I0 and terminates adjacent a scale plate 5I Thus it will be seen' that the tension of spring 44 biases lever 20 upwardly against its associated knife edge 24 and correspondingly forces boss I8 into engagement with point I6.

A stop member generally indicated at 52 is secured to the side wall of casing I0 adjacent the distal end of lever 2| and serves as a stop to limit the movement thereof in a manner to be described hereinafter.

Having reference now to lever 2| it will be seen that the same is provided, as best shown in Figure 3, With an aperture through which extends a screw 55 similar to screw 40 and likewise provided with an enlarged head 56 having projections 51 lthereon adapted to engage a lower surface of lever 2| adjacent the sides of the aperture therein. Screw 55 similarly engages a boss 58 to which is secured one end of a coil spring 59 identical to coil spring 44. The other end of spring 59 is likewise secured to a boss 60 provided with a projection 6|. A screw 52 provided with an enlarged head 63 threadedly engages boss 60. Projection 6| similarly extends exteriorly of casing I0 through a slot 62 and terminates adjacent scale plate 5|.

Thus from the foregoing it will Ibe seen that each of levers 20 and 2| is biased upwardly against their respective knife edges 29 and 30 by their respective springs 44 and 59.

Stop member 52, which also serves to limit movement of the distal end of lever 2|, is, as

better shown in Figure 4, comprised of a channel shaped member secured as at 53 by spot Welding or in any other desired manner to the side Wall of casing l0 and provided with slots 54 adjacent the ends of levers 20 and 2| wherein these ends may move.

Lever 20 is provided with an upwardly extending portion 10 which may be integral therewithl and which terminates in a attened portion 1|. extending portion 12 having at its extremity an angularly disposed lug 13 which extends in the direction of portion 10. Lug 13 thusl serves as a spacer and when portions 10 and 12 are moved in a manner to be hereinafter described the arrangement is such that they are at al1 times at least a minimum distance apart, such minimum being dened by the thickness of lug 13. Pivoted to pbrtion 12 as by pivot pin 14 is a lever 15, the extremity of which is provided with a attened portion`16 similar to, but oppositely disposed with respect to portion 1|. An elongated slot 11 in member 15 surrounds a pin 18 xedly associated with member 12 and a spring extends between a suitable aperture in a projection 8| of member 15 and a second aperture in a projection 82 of member 12. Thus it will be seen that inthe absence of external pressure thereon, members 12 and 15 move as an integral unit but `upon application of such pressure in a manner to be described hereinafter, spring 80 serves as a strain release, member 15 being permitted pivotal motion about pivot 14 to an extent defined by the limits of slot 11.

Flattened surfaces 1| and 16 are positioned on opposite sides of a pin 90, which comprises an integral portion of a member 9| pivotally secured as on a pivot screw 92 to one leg 93rof a bracket generally indicated at 94. The other leg 95 of bracket 94 carries a mercury tube switch clip 96 which in turn supports a mercury tube switch 91. A pivot pin 98, secured as indicated at 99 to the rear Wall of casing I0, passes through suitable apertures in legs 93 and 95 of bracket 94 whereby the latter is pivoted thereon. Any suitable means such as a wir'e clip |00 may be utilized to maintain bracket 94 in assembled relation with pin 98. Aset screw |0| carried by leg 93 of bracket 94 passes Lever 2| is similarly provided with an` through a suitable slotted aperture |02 in member 9| to permit suitable positioning of pin 9|] to allow for factory calibration of the instrument in a known manner. A conventional alignment pendulum |05 is positioned within and pivoted as at |06 to the rear wall of casin'g I0 in order that the instrument may be properly aligned in mounting the same.

From the foregoing the operation of the device should now be readily apparent to those skilled in the art. Assuming for the purposes of illustration that the tension in springs 44 and 59 is identical, it will be seen that upward movement of operating rod |2 is transmitted through transversely extending member ously to levers 20 and 2| and hence to members 10, 12 and 15 and that such movement in turn being transmitted through attened portions 1| and 18 to pin 90 will occasion a tilting movement of mercury switch 91. Thus an .increase in pressure in housing forcing transversely extending member I5 upwardly will rotate levers 20 and 2| simultaneously in a counter-clockwise direction as viewed in Figure 1 and through the abutment of attened surface 16 with pin 90 tilt mercury switch 91 to a position opposite that in which it is shown in Figure l, assuming, of course, that the said increase in pressure is of sucient intensity to overcome the pull exerted by springs 44 and 59. Upon a decrease in pressure however, operating rod 2 will move downwardly to permit the tension of springs 44 and 59 to rotate levers 20 and 2| respectively in a clockwise direction, as viewed in Figure l, to return the switch to the position in which it is shown in the drawing.

Assume now however that it is desired that the mercury switch assume one position upon the achievement of one temperature or pressure value and return to its opposite position upon the achievement of a second and different value.

For the purposes of illustration, assume that it is desired that mercury switch 91 tilt from the position shown in Figure 1 toits opposite position upon the achievement of a pressure in housing of, say, 5 lbs. and return to the position shown only upon the achievement of a pressure of 3 lbs., thus providing a two-pound operating differential. Screws 48 and 63 are rotated, which rotation, it will be understood, varies the tension in springs 44 and 59 respectively.

until their corresponding pointers 46 and 6| indicate the desired number of pounds on scale plate 5|.

Now it will be seen that upon an increase in pressure in housing I, operating rod |2 is moved upwardly against the combined tension of the two springs 44 and 59. However, no movement of either levers 20 or 2| takesI place until the pressure of housing is slightly in excess of 3 lbs. at which time the tension of spring 44 will be overcome. Since the tension in spring 59 is still sufficiently strong to withstand the ,pressure exerted by operating rod I2, point |1 will remain stationary while transverse member |5 is tilted about point |1 as a fulcrum lto move point |6 upward as viewed in Figures 1 and 2. Such upward movement will cause a counterclockwise rotation of lever 20 about its associated knife edge 24 and a corresponding movement of member 10 and hence flattened portion 1| in a direction away from pin. 90. Such movement will continue until the distal end of lever 20 abuts the lower portion of its associated A,,1Qt.!|whereup0n .further rotation of lever 2,0

in a counter-clockwise direction being precluded, the parts will remain stationary until such time as the pressure in housing I I increases to a point slightly in excess of 5 lbs. whereupon point Il will move upwardly against the tension of spring 59, point I6 serving as a fulcrum for member I5, and consequently rotate lever 2I in a counterclockwise direction until the distal end of lever 2I engages the lower extremity of its associated slot 54.

Such movement of lever 2I will result in a corresponding movement of member l2 and hence member T5, whereupon flat surface I6, will through its abutment with pin 90, tilt mercury switch 91 to its opposite position. Assuming now that the pressure decreases, it will be seen that as the pressure in housing II drops to a point slightly below 5 lbs. lever 2I will be moved about its associated knife edge 3D in a clockwise direction until limited by the upper portion of stop 52, in this case point I6 again serving as a ulcrum about which member I5 rotates in a clockwise direction as viewed in Figure 2. When lever 2l has reassumed the position in which it is shown in Figure 1 the parts will remain relatively motionless until the pressure has continued its descent to a point slightly below 3 lbs. whereupon, the point Il serving as a fulcrum, lever 20 will be moved in a clockwise direction by spring 44 to return member 'I0 to the position shown in Figure 1 whereupon at surface 'II will, through its engagement with pin 9U, return mercury switch 91 to the position disclosed in Figures l and 3.

It will be readily understood that by a variation on the tension of springs 40 and 59 in the manner previously described that the operating differential of the instrument may be widely varied and that either end of the operating diierential may be shifted independently of the other. It will also be readily understood that the mechanism may be advantageously utilized'either as a high pressure cutout or as a low pressure cutout dependent only upon the positioning of mercury switch 91. For example, if the switch operates as a high pressure cutout it will be so positioned that the electrodes (not shown) are in the left hand end of the switch as viewed in Figure l, whereas, if it is desired to utilize the mechanism as a low pressure cutout the electrodes will be positioned in the right hand end of the switch as seen in Figure l.

It may be here pointed out that under exceptional circiunstances such as a complete absence of pressure in housing II, operating rod l2 may drop to such an extent as to permit disalignment of member I5 with its-associated levers 20 and ZI. To preclude this happening a spring III), see Figure 2, is positioned about the upper portion of operating rod I2 and seated on an annulus III. Spring IIO thus serves to urge member I5 into engagement with its associated levers 2l) and 2| regardless of the position of operating rod I2.

From the foregoing it will now be seen that there is herein provided an apparatus accomplishing all the objects of this invention and others including many advantages of great particular utility and importance.

As many embodiments may be made of this invention and as many modifications may be made in the embodiment herein described and shown in the accompanying drawing, it is to be understood that all matterherein is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

l, In a device of the character described, in combination, a movable member, a lever freely pivoted thereon, a pair of levers movable by said rst mentioned lever, a pair of springs each biasing one of said pair of levers in a direction towards said rst mentioned lever, means for varying the tension in each of said springs and mechanism operated by said pair of levers.

2. In a device of the character described, in combination, a movable member, a transverse member pivoted thereto, a pair of levers, pivoted at the extremities of said transverse member, a pair of springs, each biasing one of said levers toward said extremities, means for varying the tension in each of said springs and mechanism operated by said pair of levers.

3. In a device of the character described, in combination, a member movable in response to variations in the value of a condition, a second member pivoted thereon, a pair of levers movable by opposite ends of said second member, resilient means biasing each of said levers towards said second member, means for varying the biasing eiect of said resilient means and mechanism operated by said levers.

4. In a device of the character described, in combination, a movable member, a second member movable thereby, levers associated with opposite ends of said-second member, means exerting a force on each of said levers, means to vary the force so exerted, and mechanism operable by said levers.

5. In a device of the character described, in

combination, a movable member, condition ren sponsive means to move said member, a transversely disposed member pivoted substantially at its mid point on said movable member, levers pivotally mounted on each end of said transversely disposed member, resilient means urging said levers towards said last mentioned member, means to vary the resiliency of said resilient means and condition control mechanism operated by said levers.

6. In a device of the character described, in combination, a movable member, a rod exerting a force on said member at an intermediate point, levers abutting said member at each extremity, fulcrums for said levers, means exerting a force on each of said levers at their extremities opposite those abutting said member, mechanism operated by said levers, and means to vary the force exerted by said means.

7. In a device of the character described, in combination, a movable member, a rod exerting a force on said member at an intermediate point, levers abutting said member at each extremity, fulcrums for said levers, means exerting a force on each of said levers at their extremities opposite those abutting said member, mechanism operated by said levers, and means to vary the force exerted by said means on the ends of each of said levers independently.

8. In a device of the character described, in combination, a movable member, a rod exerting a force on said member at an intermediate point, levers abutting said member at each extremity, fulcrums for said levers, means exerting a force on each of said levers at their extremities opposite those abutting said member, mechanism operated by said levers, means to vary the force exerted by said means on the ends of each of said levers independently, and visual means indicative of the force exerted on each of said levers.

Cil

9. In a device of the character described, in combination, switch means, means to move said switch means, said last mentioned means comprising a pin and a pairof members in abutting relationship with opposite sides of said pin, one of which serves to move said pin in one direction and the other of which serves to move said pin in the other direction, means to move each of said members independently, and means precluding the movement of said member which moves said pin prior to the movement of the other of said members in a direction away from said pin.

10. In a device of the character described, in combination, a tiltable mercury switch, means to tilt said,switch, said last mentioned means comprising a pin and a pair of members in abutting relationship in abutting opposite sides of said pin, one of which serves to move said pin and hence tilt said switch in one direction, and the other of which serves to move said pin and hence said switch in the other direction, means to move each of said members independently, and means precluding movement of said member which moves said pin prior to movement of the other of said members in a direction away from said pin.

11. In a device of the character described, in combination, a tiltablemercury switch, means to tilt said switch, said last mentioned means'comprising a pin and a pair of members in abutting relationship with opposite sides of said pin, one of which serves to move said pin and hence said mercury switch in one direction and the other of which serves to move said pin and said switch in the other direction, condition responsive means to move each of said members independently in response to changes in the value of a condition, and meansJprecluding movement of said member which moves said pin priorto movementl of the other of said members in a direction away from said pin.

12. In a device of the character described, in combination, a movable member, condition responsive means to move said member, a transversely disposed member pivoted substantially at its mid point on said movable member, levers pivotally mounted on each end of said transversely disposed member, resilient means urging said levers towards said last mentioned member, means to vary the resiliency of said resilient means and a mercury switch tiltable in one di rection by one of said levers and in the opposite direction by the other of said levers.

13. In a device of the character described, in combination, la movable member, a transverse member pivoted thereto, a pair of levers pivoted at the extremities of said transverse member, a pair of springs each comprising one of said levers towards said extremities, means for varying the tension in each of said springs, a mercury switch support, a mercury switch carried thereby, means to tilt said support, said means comprising a projection carried by each of said levers, the arrangement being such that one of said levers tilts said switch in said one direction and the other of said levers tilts said switch in the opposite direction, and condition control mechanism operated by said mercury switch.

14. In a device of the character described, in combination, a movable member, a transverse member pivoted thereto, a pair of levers pivoted at the extremities of said transverse member, a pair of springs each biasing'one of said levers towards said extremities, means for varying the tension in each of said springs, visual indicating means indicating the tension in each of said springs, a mercury switch support, a mercury switch carried thereby, means to tilt said support, said means comprising a projection carried by each of said levers, the arrangement being such that one of said levers tilts said switch in said one direction and the other of said levers tilts said switch in the opposite direction and condition control mechanism operated by said mercury switch.

15. In a device of the character described, in combination, a condition responsive device, a lever, a member operated by said condition responsive device engaging said lever at a point intermediate its ends, a rst means exerting a force on said lever on one side of said point, a second means exerting a force on said lever on the other side of said point, and switch means operated by said lever.

16. In a device of the character described, in combination, a condition responsive device, a lever, means connecting said condition responsive device with a point on said lever intermediate its ends, a rst spring tending to rotate said lever in one direction about said point, a second spring tending to rotate said lever in the other direction about said point, means for adjusting said springs, and a control device operated by said lever.

17. In a device of the character described, in combination, a condition responsive device, a lever, means connecting said condition responsive device with a point on said lever intermediate its ends, a rst spring tending to rotate said lever in one direction about said point, a second spring tending to rotatesaid lever in the other direction about said point, said springs being connected to said lever at opposite sides of said point, means for independently adjusting said springs, and switch means operated by said lever.

18. In a device of the character described comprising in combination, a mercury switch, a pivotally mounted support therefor, a pin carried by said support, a rst member engaging said pin to move it in one direction, a second member engaging said pin for moving it in the other direction, and condition responsive means for moving said first member at only one value of the condition and said second member at only another valueof the condition.

19. In a device of the character described comprising in combination, a mercury switch, a pivotally mounted support therefor, a pin carried by said support, a rst member engaging said pin to move it in one direction, a second member engaging said pin for moving it in the other direction, condition responsive means for moving said rst member at only one value of the condition and said second member at only another value of the condition, and means for independently adjusting the values of the condition at which said condition responsive means moves said rst and second members.

20. In a device of the character described comprising in combination, a switch casing, a mercury switch, a support therefor pivotally mounted within said casing, a pin carried by said support, a first member engaging said pin to move it in one direction, a second member engaging said pin to move it in the other direction, condition responsive means for moving said iirst member at one value of said condition and said second member at another value of said condition, means extending outside of said casing for independently adjusting the values of the condition at arvaege which said condition means move said rst and second members, and means outside of said casing for indicating said condition values at which said members are-moved.

21. In a device of the character described, in combination, a condition responsive device, an operating member, means operatively connecting said condition responsive device. to said operating member at an intermediate point, means exerting a force on said member at one side of said intermediate point, means exerting a force on said member at the other side of said intermediate point, said forces being exerted on said member in substantially the same direction, and switch means actuated as a result of movement of said operating member.

22. In a device of the character described, in combination, a condition responsive device, an operating member, means operatively connecting said condition responsive device to said operating member at an intermediate point, means exerting a force on said member at one side of said intermediate point, means exerting a force on said member at the other side of said intermediate point, said forces being exerted on said member in substantially the same direction, switch means actuated as a result of movement of said operating member, and means for adjusting at least one of said forces.

23. In a device of the character described, in combination, a condition responsive device, a control member, means operatively connecting said condition responsive device and anl intermediate point on said member, first and second stop means cooperating with said member, means exerting a force on a rst end of said member on one side of said intermediate point, and means exerting a force on a second end of said member on the other side of said intermediate point, said forces being exerted on said member in substantially the same direction and so proportioned that as said condition responsive device moves in one direction it causes the rst end of said member to move into cooperation with said rst stop means and then causes said second end of said member to move into cooperation with said second stop means and as said condition responsive device moves in the opposite direction it first causes said second end of said member to move out of cooperation With said second stop means and then causes said rst end of said member to move out of cooperation with said rst stop means.

24. In a device of the character described, in combination, a condition responsive device, a control member, means operatively connecting said condition responsive device and an intermediate point on said member, first and second stop means cooperating with said member, means exerting a force on a rst end of said member on one side of said intermediate point, means exerting a force on a second end of said member on the other side of said intermediate point, said forces being exerted on said member in substantially the same direction and so proportioned that as said condition responsive device moves in one direction it causes the first end of said member to move into cooperation with said rst stop means and then causes said second end of said member to move into cooperation with said second stop means, and as said condition responsive device moves in the opposite direction it rst causes said second end of said member to move out of cooperation with said second stop means and then causes said rst end of said member to move out of cooperation with said rst stop means, and means for adjusting at least one of said forces independently of the other.

25. In a device of the character described, in combination, a condition responsive device, a control member, means operatively connecting said condition responsive device and an intermediate point on said member, rst, second, third, and fourth stop means for said member, means exerting a force on a rst end of said member on one side of said intermediate point, and means exerting a force on a second end of said member on the other side of said intermediate point, said forces being exerted on said member in substantially the same direction and so proportioned that as said condition responsive device moves in one direction it causes the first end of said member to move into cooperation with said first stop means and then causes said second end of said member to move into cooperation with said second stop means, and as said condition responsive device moves in the opposite direction it rst causes said second end of said member to move out of cooperation with sai-d second stop means and into cooperation with said third stop means and then causes said rst end of said member to'move out of cooperation with said first stop means and into cooperation with said fourth stop means.

26. In a device of the character described, in combination, a condition responsive device, a control member, means operatively connecting said condition responsive device and an intermediate point on said member, first, second, third, and fourth stop means for said member, means exerting a force on a rst end of said member on one side of said intermediate point, means exerting a force on a second end of said member on the other side of said intermediate point, said forces being exerted on said member in substantially the same direction and so proportioned that as said condition responsive device moves in one direction it causes the first end of said member to move into cooperation with said first 'stop means and then causes said secondend of said member to move into cooperation with said second stop means, and as said condition responsive device moves in the opposite direction it first causes said second end of said member to move out of cooperation with said second stop means and into cooperation with said third stop means and then causes said first end of said member to move out of cooperation with said first stop means and into cooperation with said fourth stop means, and means for adjusting at least one of said forces independently of the other.

ALBERT E. BAAK. 

